Diseases of digestive system are frequently encountering diseases, in which the incidence rate of peptic ulcer is 10-12% relative to the total population. Gastric acid is the main reason for the peptic ulcer. The preliminary treatment methods mainly comprise of antacids (such as sodium bicarbonate, aluminum hydroxide, etc.) to neutralize gastric acid to alleviate symptoms. Since the 1970s, the discovery of gastric acid secretion inhibitors such as H2 receptor blocking agents, proton pump inhibitors, etc. brings a new era of peptic ulcer treatment. These drugs induce irreversible inhibition of H+, K+-ATP enzymes of secretory microtubules constituting parietal cell top membrane and tubular bubbles in cytoplasm, thereby effectively inhibiting gastric secretion, and thus they have merits of quick onset and high ulcer healing rate that can significantly reduce surgery rate.
U.S. Pat. No. 4,255,431 discloses a compound of Formula A, i.e., Omeprazole.

Omeprazole is the first marketed proton pump inhibitor, and gradually prevailed in competition with H2 receptor antagonist in antiulcer drug market, becomes the first best-selling drug in 1996 due to its unique therapeutic effect, and at the top of list for several consecutive years. Following Omeprazole, many new proton pump inhibitors are continuously marketed, including Lansoprazole, Pantoprazole, Rabeprazole and Esomeprazole.
Patent EP0268956 discloses a compound of Formula B, i.e., Rabeprazole.

Rabeprazole was marketed in Japan in 1997, and China in 2001, which has an activity against gastric acid secretion in vitro 2-10 times that of Omeprazole, and more quick and significant therapeutically effects. Rabeprazole can be quickly activated, and achieve the maximum acid inhibition effect within 5 min, but its duration of action is shorter than that of Omeprazole.
GB2174988 discloses the following compound 81:

However, proton pump inhibitors have a relatively long time to achieve the strongest effect, the maximum acid inhibition effect can only be achieved after 3-5 days at therapeutically dose, and these drugs may have significant interaction with other drugs, and great individual difference in pharmacokinetics.
Hence, it is still in need to develop new proton pump inhibitors that have quick onset of action, good acid inhibition effect, less interaction with other drugs and small individual difference.